Dug into the very helpful articles, again thank you. I pressed firmly on the CPU ASIC. It seems seated well. I have pressed firmly on both sides of the ribbon cable, it also seems seated well. Problem still exists.
To isolate the lamps from the board, I removed connectors J133, J137, and J138. I then turned on the machine, set it to single lamp test mode, lamp 11 (P in PAID, Row 1, J133-1, Column 1, J137-1; this was a NON problematic lamp). I connected a test light (no diode or lamp from table, traditional electrical test light) with alligator clip to J137-1 (the column 1 for lamp 11), and touched prob to J133-1 (the row 1 for lamp 11). Test lamp lit (pulse lighting). Probing other pins on J133 and J137/8, all good (test light did NOT light), testing continuity on transistors Q83-90 (TIP-102) only showed continuity (pulsing) on correct transistor Q90, testing continuity transistors Q91-98 (TIP 107) had continuity on all (solid). This seems strange to me that they all had continuity, but maybe that's expected.
I then changed single lamp test to a problematic lamp, lamp 16 (right jet, Row 6, J133-7, Column 1, J137-1). I connected a test light with alligator clip to J137-1 (the column 1 for lamp 16), and touched prob to J133-7 (the row 6 for lamp 16). Test lamp lit (pulse lighting). But also touching J133-9 (lamp 18, admit one, Row 8, 133-9, Column 1, 137-1), also lit up (pulse lighting). Not other pins on J133 lit up. This mimics what I'm seeing on the play field lamps. So I would thing with connectors J133, J137, and J138 disconnected, and seeing the problems right at the pins, rules out and shorts in the play field, or a lamp diode pressing against metal. Correct?
With the machine on, still in single lamp mode test with lamp 16 under test, I began to test the transistors by putting my DMM in continuity mode, touching the 18V lamp matrix test point (TP8), and touching row 6 transistor Q85. Had continuity (pulsing). But I also probed row 8 transistor Q83, and also had continuity (pulsing). Did NOT have continuity on any of the other Q transistors related to the rows (Q84, Q86-90). So this appears to also mimic what I'm seeing on the play field that both transistors are "firing" when only one should. Again strange to me, when I probed any of the column transistors (Q91-98), they all had continuity (this was still with machine on in single lamp mode test on lamp 16). I would have only expected column Q91 transistor to have continuity, but maybe this is expected. Transistors Q83-Q90 are TIP-102 Transistors, Transistors 91-98 are TIP-107 Transistors
The Williams WPC PinWiki link says for a transistor test: "If the game has an entire column of lamps locked on, there is a good chance that a lamp column transistor has shorted. Testing for this condition is very simple. Set your DMM to continuity. Touch one probe to the 18V lamp matrix test point as pictured at left. Touch the other probe to the tab of each of the TIP-107 transistors. Any that "buzz" are shorted and will need to be replaced."
I'm not having an entire column, I'm having two lamps on same column light, for rows 6 & 8, as I step though each lamp on row 6 & 8. For example, col 1 row 6 & 8 lamps light when each is in test mode. col 2 row 6 & 8 lamps light, etc, etc. I'm not sure if the Williams WPC PinWiki link transistor test meant for machine to be on or off. With it off, no continuity on and of the transistors.
Not quite sure what exactly this is all pointing to, other that ruling out any wire shorts or lamp diode touching a bracket problem, and likely a board problem. Just don't yet understand what this is pointing to in the board.
Additionally, maybe related, maybe not. When I turn on the machine, I'll see led on board behind the back glass light, my DMD comes on quickly, my Raspberry Pi & TV (for the creature mod) power on quickly. But the play field takes a LONG time (~5 mins), and I hear a rapid, steady, soft clicking (2-3 clicks a sec) in the speaker. Then it stops, play field lights come on, and the first start up creature sound plays. This is also very odd to me, has existed before the lamp problem, but hadn't affected play in the past, prior to lamp problem.
Does any of these tests explain anything. Basically, I think I'm seeing two row transistors fire when only one should. But not understanding cause, as transistors seem ok.